The A&ultima SP4000 is Astell&Kern’s newest flagship digital audio player, the result of three years of relentless research and innovation following the development of the SP3000.As part of the A&ultima series—Astell&Kern’s flagship line-up combining cutting-edge technology and top-tier specifications—the SP4000 surpasses the boundaries set by the SP3000, once regarded as the ultimate reference.

Built upon an advanced Octa audio circuit architecture, the SP4000 distils the purest essence of audio engineering, delivering a sound experience unlike anything before it—refined, powerful, and remarkably close to perfection. Discover the SP4000 and experience sound on an entirely new level.

Octa Audio Circuit Architecture

In the SP3000, the digital-to-analog signal processing structure was separated in a 1:2 ratio. With the SP4000, it has evolved into a 1:1 architecture.
This new structure, where one AK4191 digital processor is paired with one AK4499EX DAC, allows digital signals to be delivered precisely to a single DAC without the need to distribute noise, enabling improved signal separation and processing.

Through continuous research and innovation in circuit technology, the SP4000 successfully implements a true Quad DAC—a feat previously considered impossible due to noise and other issues. As a result, the SP4000 achieves an impressive SNR (Signal-to-Noise Ratio) of 131dB, on par with the independent dual audio circuit of its predecessor.

High Drivin2g Mode

The SP4000 features twice as many OPAMPs arranged in parallel compared to its predecessor, delivering richer and more detailed sound. High Driving Mode provides powerful and stable output—much like a four-wheel-drive vehicle confidently navigating rough terrain. It’s designed to reproduce even the most delicate sonic details with precision, allowing you to enjoy deeper, clearer, and more immersive music.

High-End Shrunken Calfskin Case

The SP4000 is packaged with a premium leather case crafted from Shrunken Calf by Perlinger, Germany’s world-renowned leather house. Founded in 1864 and spanning five generations of craftsmanship, Perlinger supplies the finest leather to luxury brands across the globe—blending time-honoured tradition with modern techniques.

The Shrunken Calf leather used in the case is made from the soft, delicate hide of calves under one year old. It is processed using a chrome tanning method to preserve its natural texture, then uniquely shrunk using special agents—not heat—to retain its organic grain and wrinkles.

Following an aniline dyeing process, Perlinger’s proprietary pigments are added to achieve a deep, vibrant color. Their advanced anti-aging treatment ensures that this richness lasts over time, complementing the SP4000 with a leather case that embodies lasting beauty, durability, and luxury.